Supermolecular carboplatin derivatives, their preparation and pharmaceutical composition containing them as active ingredient and applications of the compositions

ABSTRACT

The present invention relates to a novel class of supermolecular carboplatin derivatives represented by general formula (I), wherein B is a polycarboxylic acid represented by general formula (II), wherein R 1 , R 2  and n are defined as in the description. The present invention also relates to a process for preparing the same, pharmaceutical compositions containing the same as active ingredient and the use of the derivatives in the preparation of pharmaceutical compositions which are useful in treating various cellular cancers including hepatoma, stomach cancer, lung cancer and the like. The derivatives have stable cage-like chemical structures and constitutions in solid and in aqueous solution. The derivatives can not only kill cancer cells at a rate significantly higher than that by carboplatin, in particular, in the case of hepatoma cells, at a rate one to two times higher than that by carboplatin, but also produce little side effects such as vomit, baldness, decreases of leucocytes and platelets, and the like, which can be induced by administration of other chemotherapeutics. In the acute toxicity tests on mice, the lethal dose (LD 50 ) of the present derivatives is about 300 mg/kg and 260 mg/kg body weight for a subcutaneous(sc) and an intraperitoneal(ip) administration, respectively. Therefore, the present derivatives are a novel class of cis-platium which can be widely used as anticancer agents.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a 371 filing of PCT/CN01/01595 filed Nov. 30, 2001,which is herein incorporated by reference in its entirety.

TECHNICAL FIELD

The present invention relates to a novel class of supermolecularcarboplatin derivatives, the preparation of such derivatives, apharmaceutical composition containing them as active ingredient, and useof the derivatives and pharmaceutical compositions containing them forthe clinical treatment of various cellular cancers such as hepatoma,stomach cancer, lung cancer and the like.

BACKGROUND ART

Platinum-containing anticancer drugs have attracted the attention ofscientists from many countries since Rosenberg and Camp firstly reportedthe anticancer effect of cisplatinum[Cis-Pt(NH₃)₂Cl₂] in 1969 (Trans.Met. Chem., 1987:14, 77). In the last 30 years, tens ofplatinum-containing anticancerdrugs have been successfully developed andapplied in clinical treatment of cancers, such as Iproplatin(GB1578323), Oxaliplatin (J. Med. Chem., 1978:21, 1315), Ormaplatin (J.Med. Chem., 1978:21, 1315), Labaplatin (EP176005), Carboplatin(GB20244823) and the like. However, these drugs are in advantageous inthat their stability in aqueous solution is not so good and thus theycannot used in the form of oral preparations; they have high toxicity tohuman body and thus result in many serious toxic reactions in stomach,kidney, blood and the like. Therefore, novel cisplatinum-derivedcompounds without the above-mentioned defects have been investigated bypharmaceutical specialists all over the world for many years, but up tonow, there is no substantive progress.

In 1978, J. M. Lehn proposed a new concept that weak intermolecularinteractions form supermolecular compounds, that is to say, molecules,when bound via a non-covalent force (such as hydrogen bond, coordinationbond, van der Waals force, electrostatic attraction, etc.), formmolecular aggregates, which exhibit new physicochemical activities suchas selectivity, identifiability and migration, and are named as“supermolecular compound”. C. J. Peterson, D. J. Cram and Lehn wereawarded the Nobel Prize for chemistry in 1987 for their greatachievements in supermolecular compounds including crown ethers,cryptands and the like (J. M. Lehn, Angew. Chem., Inter. Ed. Engl., 27,89, 1988). However, researches concerning the chemical structures of thesupermolecular drugs proposed by the present inventors have not beendisclosed in prior art.

SUMMARY OF THE INVENTION

Based on the theory of supermolecular chemistry, the present inventorshave firstly and successfully designed and synthesized a class ofcage-like supermolecular carboplatin anticancer drugs formed by hydrogenand coordination bonds.

Therefore, an object of the present invention is to provide a novelclass of supermolecular carboplatin derivatives.

Another object of the present invention is to provide a process forpreparing said supermolecular carboplatin derivatives.

Another object of the present invention is to provide a pharmaceuticalcomposition comprising as active ingredient said supermolecularcarboplatin derivatives.

Still another object of the present invention is to provide the use ofsaid supermolecular carboplatin derivatives for the clinical treatmentof cellular cancers such as hepatoma, stomach cancer, lung cancer andthe like.

DETAILED DESCRIPTION OF THE INVENTION

In one aspect, the present invention provides a supermolecularcarboplatin derivative represented by general formula (I):

which is a supermolecular compound consisting of a host componentA—carboplatin and a guest component B bound via intermolecular hydrogenbonds, wherein the guest component B is a polycarboxylic acidrepresented by general formula (II):

wherein R₁ and R₂ may be same or different from one another, andindependently represent hydrogen, hydroxy, carboxy, phenyl or3,5-dicarboxyphenyl, n represents an integer of from 0 to 3, with theproviso that R₁ and R₂ on the same carbon atom cannot be hydroxy orcarboxy at the same time, and if n is 2, a double bond may exist betweenthe two carbon atoms, or R₁ and R₂ may form together with the carbonatom to which they are attached a cyclohexane ring or a benzene ringoptionally substituted by one or two further carboxy.

The guest component B is preferably selected from the group consistingof oxalic acid, 1,3-propanedioic acid, 1,4-butanedioic acid,1,5-pentanedioic acid, cis-butenedioic acid, 2-hydroxy-1,4-butanedioicacid(malic acid), 2,3-dihydroxy-1,4-butanedioic acid(tartaric acid),2-phenyl-1,3-propanedioic acid, 1,2-dicarboxycyclohexane,3-hydroxy-3-carboxy-1,5-pentanedioic acid(citric acid), phthalic acid,1,3,4-benzene-tricarboxylic acid and 1,2,4,5-benzenetetracarboxylicacid, with oxalic acid, 1,3-propanedioic acid, 1,4-butanedioic acid,2-phenyl-1,3-propanedioic acid, tartaric acid, malic acid or citric acidbeing more preferred.

Preferably in the compound of general formula (I), the host componentA—carboplatin is bound with the guest component B by multiple hydrogenbonds, thereby forming a supermolecular compound with a cage-likespatial structure. For example, when the guest component B isphenylmalonic acid, a supermolecular compound having following generalformula (III) is obtained,

The supermolecular compound A—B represented by general formula (I)according to the present invention is stable both in solid and inaqueous solution, without dissociation. It is confirmed by spectralanalysis, such as UV, IR, NMR, MS, X-ray monomorphic diffraction and thelike, that the supermolecular compound according to the presentinvention is not a mixture, but a novel molecular compound having asingle molecular weight, a stable element composition and stablespectral characteristics. The N atom in the intramolecular-NH₃ group isin a valence of +5, and thus cannot form a salt (—NH₄) with H⁺; the Hatom in the carboxy group of the guest component B forms intramolecularhydrogen bonds with the carbonyl group of the host component A; and atthe same time, the H atom in the amino group —NH₃ of the host componentA forms intramolecular hydrogen bonds with the carbonyl group of theguest component B, thereby constructing the supermolecular compoundrepresented by general formula (I).

In another aspect, the present invention provides a process forpreparing the compound represented by general formula (I), whichcomprises the steps of:

-   -   a) preparing aqueous solutions of the host component        A—carboplatin and the guest component B, respectively, with        their molar concentrations being equal;    -   b) mixing in equal molar amounts the two starting solutions at a        temperature of 4 to 40° C., stirring homogeneously, sterilized        and filtered, and    -   c) diluting the solution obtained in step b) with pure water,        followed by direct sealing as an aqueous injection of 50 mg/5        ml, or concentrating the aqueous product solution at a        temperature below 40° C. and then drying to form a solid powder.

In the process according to the present invention, the reaction in stepb) is preferably carried out at a pH of from 2 to 4, and in order tokeep the pH in such a range, a certain amount of component B can beused.

The present invention also relates to a pharmaceutical composition forthe treatment of various cellular cancers, comprising as activeingredient the compound represented by general formula (I) according tothe present invention and a pharmaceutically acceptable carrier. Saidpharmaceutical composition can be formulated into dosage forms such astablets, capsules, pills, oral solutions and the like.

The present invention further relates to use of the supermolecularcompound represented by general formula (I) for the clinical treatmentof various cellular cancers such as hepatoma, stomach cancer, lungcancer and the like.

The supermolecular compound represented by general formula (I) accordingto the present invention exhibits high selectivity for cancer cells.Tests on human cancer cells incubated in vitro show that thesupermolecular compound according to the present invention kills variouscancer cells such as of liver, stomach, colon, large intestine,pancreas, breast and lung cancer at a rate significantly higher thanthat by carboplatin, in particular, in the case of hepatoma, at a rateone to two times higher than that by carboplatin, with IC₅₀ being about10-15? g/ml. The test method and the results are shown below.

Method:

The test is carried out in accordance with the internationally acceptedpharmacodynamic cytotoxic assay. The drug to be tested is diluted to adesired concentration using 15% fetal calf serum RPMI-1640 medium,filtered and sterilized through an aseptic membrane, and then formulatedto provide concentration gradients of 200, 100, 50 and 10? g/ml. Theresulting solutions are added to a microtiter plate containing variousincubated human cancer cells, and then are incubated for 72 hours. Toeach well of the plate is added 0.5? l 0.2% MTT solution, and after 4hours, DMSO is added to develop color. The absorbance of each well istaken using Model 250 microplate reader, from which the fatality ratesof cancer cells and IC₅₀ values are calculated.

Results of Fatality Rates of Cancer Cells:

Concentration Carboplatin ?g/ml SMAN¹ SMAM² SMAT³ (KP) Fatality rates(%)from MTT test on SMMC-7721 hepatoma cells 10 16.6 4.8 — — 50 23.6 22.08.5 2.3 100 44.0 25.8 15.2 11.3 200 75.2 67.9 51.0 28.4 Fatalityrates(%) from MTT test on SGC-7921 stomach cancer cells 10 5.8 — — — 5057.5 39.4 29.2 15.0 100 82.0 72.0 55.8 40.0 200 91.0 88.6 84.4 81.0Fatality rates(%) from MTT test on LS-1747 colon cancer cells 10 3.6 2.17.4 2.3 50 12.0 2.7 10.5 7.9 100 54.0 41.5 36.8 11.3 200 69.8 56.0 —32.0 Fatality rates(%) from MTT test on PC-14 lung cancer cells 10 — — —— 50 — — — — 100 40.9 35.7 38.0 16.3 200 43.7 42.6 46.0 39.4 Fatalityrates(%) from MTT test onRCAP-37 human breast cancer cells 50 3.0 — — 2100 17 8 6 4 200 38 23 16 14.7 Note: ¹supermolecular compound formed bycarboplatin and citric acid ²supermolecular compound formed bycarboplatin and malic acid ³supermolecular compound formed bycarboplatin and tartaric acid

The supermolecular compound represented by general formula (I) accordingto the present invention exhibits little or no toxic side effects suchas vomit, baldness, decreases of leucocytes and platelets, and the like,which can be induced by administration of other chemotherapeutics, andtheir toxicity on normal human proteins, biomembranes, DNA and RNA isabout ½ of carboplatin. For example, the LD₅₀ values of thesupermolecular compound represented by general formula (I) according tothe present invention by subcutaneous injection(sc) and intraperitonealinjection(ip) in albino mice are measured as follows.

Method:

50 Kunming mice weighing 18-22 g are randomized to 5 groups of 10 mice.Single subcutaneous injection(sc) is effected in mice using the drug tobe tested at doses of 400, 300, 200, 100, 50 mg/kg. Observation lastsfor 14 days, and mortality of each group is recorded. The LD₅₀ value iscalculated according to Kurber method. Likewise, the LD₅₀ value forintraperitoneal injection (ip) is calculated.

Results:

SMAN (supermolecular compound formed by carboplatin and citric acid) istaken by way of example, the LD₅₀ values for subcutaneous injection(sc)and intraperitoneal injection (ip) in albino mice are 300 mg/kg and 260mg/kg, respectively. The mice die after 3 to 7 days.

Time of death(days) 1 2 3 4 5 6 7 Mortality, % Time of death andmortality(%) in mice(SMAN, s.c.) 400 mg/kg 1 1 2 3 3 100 300 mg/kg 1 2 31 70 300 mg/kg 1 3 1 50 100 mg/kg 0 Time of death and mortality(%) inmice(SMAN, i.p.) 400 mg/kg 1 4 5 100 300 mg/kg 2 3 50 300 mg/kg 1 10 100mg/kg 0

Although the anticancer mechanism of the compound according to thepresent invention is not fully determined, it is believed that thefollowing explanations can be made according to the modern molecularbiology. The key points of pharmaceutical molecular design lie in that ahost component A effective against cancers and a guest component Bcapable of forming a supermolecular cage with the component A must bepresent so as to form a supermolecular cage-like compound bycoordination and hydrogen bonds, which cage should be relatively stableand not dissociated in aqueous solutions and body fluid, and only whenencountering structurally abnormal DNA in cancer cells, become openeddue to the induction of free base of the abnormal DNA such as adenine,thereby releasing the active host component A to kill cancer cells.According to such an assumption, the host component A in the presentinvention is designed to be carboplatin which clinically kills cancercells and is relatively low in toxicity; and the guest component Bshould contain polycarboxylic acid group in its structure, and can bebound with the host component A by multiple hydrogen bonds to form thecage-like supermolecule A—B, which retains the relatively stablecage-like structure in body fluid and cells without dissociation,showing no “toxicity” of the host component A to proteins, membranes andnormal DNA and RNA. When the supermolecule A—B encounters cancer cells,local hydrogen bonds in the duplex DNA structure in cancer cells wouldbe destructed, thereby exposing free bases, which in turn inducesopening of hydrogen bonds in the supermolecule A—B, and the release ofthe host component A, with the Pt atom in the host component binding tothe exposed base of purine in structurally abnormal DNA, thuseffectively interrupting the DNA replication and transcription in cancercells. The procedure can be summarized as below:

EXAMPLES

The present invention is illustrated in detail by making reference tothe following examples, but would not be limited by them.

Example 1

Supermolecular Compound of Phenylmalonic Acid-Carboplatin (SMAP)

Host component A: carboplatin

Guest component B: phenylmalonic acid

Product: supermolecular phenylmalonic acid-carboplatin A—B

Molecular formula: C₁₅H₂₀O₈N₂Pt

Molecular weight: 551

Chemical structure:

Synthesis:

Preparation of SMAP: 371 parts by weight of starting componentA(carboplatin) and 180 parts by weight of starting component B(phenylmalonic acid) are respectively formulated into aqueous solutionsof the equal molar concentration. The resulting solutions are then mixedin an equal molar amount at a temperature of 25° C., stirredhomogeneously, sterilized and filtered. The aqueous product solution isconcentrated at a temperature below 40° C. and dried to afford solidSMAP powder.

-   -   Aqueous solution, pH 2.5, T=25° C.

1 mol A+1 mol B --------------------? 1 mol A—B

Appearance:

white crystalline powder; solubility in water: 3.5%; pH: 2.5-3.0; poorsolubility in alcohols and other organic solvents; unstable to light andheat.

Spectral Analysis:

UV: ?_(max)=245 nm (Aqueous solution);

IR: KBr disc, main absorption peaks (cm⁻¹): 3269 s, 1648 s, 1612 m, 1500m, 1381 s, 1349 m;

¹H-NMR (500 MHz, DMSO): ?1.6 (2H in host A, quintet), 2.6 (4H in host A,triplet), 4.1 (6H on two N atoms in host A, singlet), 5.8 (CH in guestB), 7.4(5H of benzene ring in guest B), 12.3 (1H of carboxy in guest B);

MS: ESI-MS, quasi-molecular ion peak M-1 in negative ion mass spectrum:m/z 550.

Pharmacological Activities:

Fatalityrate of multiple cancer cells in lung cancer, hepatoma andstomach cancer: 50-70%.

Toxicity:

The LD₅₀ by subcutaneous injection(sc) and intraperitoneal injection(ip)in mice are respectively 290 mg/kg and 250 mg/kg.

Stability:

SMAP can keep stable for a long term in solid and for 8 hours in aqueoussolution.

Example 2

Supermolecular Compound of Tartaric Acid-Carboplatin (SMAT)

Host component A: carboplatin

Guest component B: tartaric acid

Product: supermolecular tartaric acid-carboplatin A—B

Molecular formula: C₁₀H₁₈O₁₀N₂Pt

Molecular weight: 521

Chemical structure:

Synthesis:

Preparation of SMAT: 371 parts by weight of starting component A(carboplatin) and 150 parts by weight of starting component B (tartaricacid) are respectively formulated into aqueous solutions of the equalmolar concentration. The resulting solutions are then mixed in an equalmolar amount at a temperature of 25° C., stirred homogeneously,sterilized, filtered and diluted with pure water, then directly sealedin the form of an aqueous SMAT injection of 50 mg/5 ml, or the aqueousproduct solution is concentrated at a temperature below 40° C. and driedto afford solid powder.

-   -   Aqueous solution, pH 2.5, T=25° C.

1 mol A+1 mol B --------------------? 1 mol A—B

Appearance:

white crystalline powder; solubility in water: 3.5%; pH: 2.5-3.0; poorsolubility in alcohols and other organic solvents; unstable to light andheat.

Spectral Analysis:

UV: ?max=225 nm (shoulder peak, Aqueous solution);

IR: KBr disc, main absorption peaks (cm⁻¹): 3269 s, 1648 s, 1612 m, 1381s, 1349 m;

¹H-NMR (500 MHz, DMSO): ?1.6 (2H in host A, quintet), 2.6 (4H in host A,triplet), 4.1 (6H on two N atoms in host A, singlet), 4.2 (2CH in guestB), 12.6 (1H of carboxy in guest B);

MS: ESI-MS, quasi-molecular ion peak M-1 in negative ion mass spectrum:m/z 520.

Pharmacological Activities:

Fatality rate of multiple cancer cells in lung cancer, hepatoma andstomach cancer: 60-80%.

Toxicity:

The LD₅₀ by subcutaneous injection(sc) and intraperitoneal injection(ip)in mice are respectively 290 mg/kg and 250 mg/kg.

Stability:

SMAT can keep stable both in aqueous solution and in solid for a longterm.

Example 3

Supermolecular Compound of Malic Acid and Carboplatin (SMAM)

Host component A: carboplatin

Guest component B: malic acid

Product: supermolecular malic acid-carboplatin A—B

Molecular formula: C₁₀H₁₈O₉N₂Pt

Molecular weight: 505

Chemical structure:

Synthesis:

Preparation of SMAM: 371 parts by weight of starting component A(carboplatin) and 134 parts by weight of starting component B (malicacid) are respectively formulated into aqueous solutions of the equalmolar concentration. The resulting solutions are then mixed in an equalmolar amount at a temperature of 25° C., stirred homogeneously,sterilized, filtered and diluted with pure water, then directly sealedin the form of an aqueous SMAM injection of 50 mg/5 ml, or the aqueousproduct solution is concentrated at a temperature below 40° C. and driedto afford solid powder.

-   -   Aqueous solution, pH 2.5, T=25° C.

1 mol A+1 mol B -------------------------? 1 mol A—B

Appearance:

white crystalline powder; solubility in water: 3.5%; pH: 2.5-3.0; poorsolubility in alcohols and other organic solvents; and unstable to lightand heat.

Spectral Analysis:

UV: ?max=225 nm (shoulder peak, Aqueous solution);

IR: KBr disc, main absorption peaks (cm⁻¹): 3269 s, 1648 s, 1612 m, 1500m, 1381 s, 1349 m;

¹H-NMR (500 MHz, DMSO): ?1.6 (2H in host A, quintet), 2.6 (4H in host A,triplet), 4.1 (6H on two N atoms in host A, singlet), 4.2 (CH₂ in guestB, doublet), 4.3 (CH in guest B, quartet), 12.6 (1H of carboxy in guestB);

MS: ESI-MS, quasi-molecular ion peak M-1 in negative ion mass spectrum:m/z 504.

Pharmacological Activities:

Fatality rate of multiple cancer cells in lung cancer, hepatoma andstomach cancer: 50-80%.

Toxicity:

The LD₅₀ by subcutaneous injection(sc) and intraperitoneal injection(ip)in mice are respectively 290 mg/kgand 250 mg/kg.

Stability:

SMAM can keep stable both in aqueous solution and in solid for a longterm.

Example 4

Supermolecular Compound of Citric Acid and Carboplatin (SMAN)

Host component A: carboplatin

Guest component B: citric acid

Product: supermolecular citric acid-carboplatin A—B

Molecular formula: C₁₂H₂₀O₁, N₂Pt

Molecular weight: 563

Chemical structure:

Synthesis:

Preparation of SMAN: 371 parts by weight of starting component A(carboplatin) and 192 parts by weight of starting component B (citricacid) are respectively formulated into aqueous solutions of the equalmolar concentration. The resulting solutions are then mixed in an equalmolar amount at a temperature of 25° C., stirred homogeneously,sterilized, filtered and diluted with pure water, then directly sealedin the form of an aqueous SMAN injection of 50 mg/5 ml , or the aqueousproduct solution is concentrated at a temperature below 40° C. and driedto afford solid powder.

-   -   Aqueous solution, pH 2.5, T=25?

1 mol A+1 mol B -------------------------? 1 mol A—B

Appearance:

white crystalline powder; soluble in water and poorly soluble inalcohols and other organic solvents.

Spectral Analysis:

UV: ?max=225 nm (shoulder peak, Aqueous solution);

IR: KBr disc, main absorption peaks (cm⁻¹): 3269 s, 1648 s, 1610 s, 1384s, 1349 m;

¹H-NMR (500 MHz, DMSO): ?1.6 (2H in host A, quintet), 2.6 (4H in host A,triplet), 4.1 (6H on two N atoms in host A, singlet), 4.2 (2magnetically unequivalent CH₂ in guest B), 12.6(1H of carboxy in guestB);

MS: ESI-MS, quasi-molecular ion peak M-1 in negative ion mass spectrum:m/z 562.

Pharmacological Activities:

Fatality rate of multiple cancer cells in lung cancer, hepatoma andstomach cancer: 50-90%.

Toxicity:

The LD₅₀ by subcutaneous injection(sc) and intraperitoneal injection(ip)in mice are respectively 300 mg/kg and 260 mg/kg.

Stability:

SMAN can keep stable both in aqueous solution and in solid for a longterm.

1. A compound represented by general formula (I),

which is a supermolecular compound consisting of a host componentA—carboplatin and a guest component B bound via intermolecular hydrogenbonds, wherein the guest component B is a polycarboxylic acidrepresented by general formula (II):

wherein R1 and R2 may be the same or different from one another, andindependently represent hydrogen, hydroxy, carboxy, phenyl or3,5-dicarboxyphenyl, n represents an integer of from 0 to 3, with theproviso, that R₁ and R₂ on the same carbon atom cannot be hydroxy orcarboxy at the same time, and if n is 2, a double bond may exist betweenthe two carbon atoms, or R₁ and R₂ may form together with the carbonatom to which they are attached a cyclohexane ring or a benzene ringoptionally substituted by one or two further carboxys.
 2. The compoundrepresented by general formula (I) according to claim 1, wherein thehost component A—carboplatin is bound with a guest component B bymultiple hydrogen bonds, thereby constructing a supermolecular compoundwith a cage-like spatial structure.
 3. The compound represented bygeneral formula (I) according to claim 1, wherein the guest component Bis selected from the group consisting of oxalic acid, 1,3-propanedioicacid, 1,4-butanedioic acid, 1,5-pentanedioic acid, cis-butenedioic acid,2-hydroxy-1,4-butanedioic acid (malic acid),2,3-dihydroxy-1,4-butanedioic acid (tartaric acid),2-phenyl-1,3-propanedioic acid, 1,2-dicarboxycyclohexane,3-hydroxy-3-carboxy-1,5-pentanedioic acid (citric acid), phthalic acid,1,3,4-benzenetricarboxylic acid and 1,2,4,5-benzenetetracarboxylic acid.4. The compound represented by general formula (I) according to claim 3,wherein the guest component B is oxalic acid, 1,3-propanedioic acid,1,4-butanedioic acid, phenylmalonic acid, tartaric acid, malic acid orcitric acid.
 5. The compound of formula (I) according to claim 4,wherein the guest component B is phenylmalonic acid and thesupermolecular compound has a structural formula (III):


6. A process for preparing the compound represented for general formula(I) according to claim 1, which comprises the steps of: d) preparingaqueous solutions of the host component carboplatin and the guestcomponent B, respectively, with their molar concentrations being equal;e) mixing in equal molar amounts the two starting solutions at atemperature of 4 to 40° C., stirring homogeneously, sterilized andfiltered, and f) diluting the solution obtained in step b) with purewater, followed by direct sealing as an aqueous injection of 50 mg/5 ml,or concentrating the aqueous product solution at a temperature below 40°C. and then drying to form a solid powder.
 7. The process according toclaim 6, wherein the reaction in step b) is carried out at pH 2-5.
 8. Apharmaceutical composition for treating cellular cancers, comprising asactive ingredient the compound according to claim 1, and apharmaceutical acceptable carrier.